This invention relates to a particle analyzing apparatus which provides information valuable for use in clinical diagnosis or the like by introducing a parameter which clearly shows the characterizing features of a particle in the analysis of particles such as blood cells.
So-called particle size distributions, in which a distribution of the sizes of particles under measurement is obtained and expressed as a histogram of the frequency of occurrence of particles with respect to size, find use in the industrial field and in various other fields as well.
Automatic particle analyzers are adapted to pass particles one at a time through a very small detecting area and detect electric signal pulses, each of which corresponds to the size of a discrete particle passing through the detecting area. Since such an apparatus makes it possible to obtain a particle size distribution very simply from information relating to the heights of the pulses, the fields of application of the apparatus has broadened considerably.
A so-called sheath-flow analyzer for measuring particles by passing them through the center of a detecting area, in a precise ordered array of a single file, is utilized also in the field of clinical diagnosis. This analyzer provides a highly accurate particle size distribution and is being positively applied in clinical diagnosis by measuring the particle size distribution of red blood cells, white blood cells and platelets in blood.
A problem with the prior art is that since use is made solely of particle size information, i.e., pulse height information, there is a limitation upon the usefulness of a particle size distribution in that, when attempting to diagnose a particular type of anemia, a particle size distribution does not make it possible to clearly distinguish between, say, iron-deficiency anemia and thalassemia.
An apparatus adapted to utilize pulse width as information, in addition to pulse height information, has been proposed. An apparatus of this kind has been disclosed in Japanese Patent Application Public Disclosure (KOKAI) No. 230139/1984, by way of example. The apparatus is capable of identifying blood cell type, or of distinguishing between blood cells and noise, by utilizing information relating to pulse height and width. Nevertheless, the disclosure is silent upon the aforementioned problem relating to analysis of blood cell particle size distribution, and does not mention any improvements in blood cell particle size distributions. In addition, nowhere does the disclosure describe a technique for applying an improved blood cell particle size distribution to diagnosis for identifying a particular type of anemia by name.
Japanese Patent Application Public Disclosure (KOKAI) Nos. 79834/1984 and 81536/1984 disclose an apparatus equipped with circuitry for detecting pulse height, area and width, in which logarithms, products, ratios, differences, sums or combinations thereof are processed with regard to each output produced. However, these disclosures in fact do nothing more than describe signal processing circuits and are silent upon techniques for applying the art to the clinical field, as for the purpose of diagnosing types of anemia by name.
More specifically, all of the aforementioned disclosures differ from the present invention in terms of their purpose, and therefore only describe that pulse width is merely detected as additional information to supplement pulse height information. These disclosures are not concerned with the true significance of detecting pulse width and the usefulness of such detection.